1. Field of the Invention
The present invention relates to ovens, such as ovens for cooking foods, having an opening which can be closed by a hinged door.
2. Description of the Prior Art
In traditional ovens, the door is a rigid frame hinged along one of its sides to the edge of the oven enclosure. A peripheral seal provides sealing between the inner face of the door and the enclosure in the closed position. The door generally has a central wall made from a transparent material, surrounded by the frame to which it is fixed.
A first problem which is raised in traditional ovens is the rise in temperature of the door, which is in contact with the oven enclosure and heats up by conduction. The central part of the door forms directly an enclosure limiting wall and heats up by radiation and convection. Thus, for manipulating the door external handles are provided which are sufficiently insulated thermally from the rest of the door. Apart from the space required and aesthetic drawbacks inherent in such external handles, it will be readily understood that the relatively high temperature of the door itself forms a dangerous element since the user may touch the door accidentally.
Furthermore, in traditional ovens, it is observed that the door frame, very often made from metal, tends to be deformed and to buckle because of the temperature, so that closure becomes defective. Such a structure is unsuitable for complying with the severe sealing requirements in modern ovens in which cooking may be steam cooking.
A second problem raised in traditional ovens is the difficulty of obtaining sufficient sealing between the oven door and the oven enclosure, particularly in steam ovens. In fact, it is necessary to prevent steam from escaping during operation of the oven. Such sealing is made difficult by the differential expansion between the oven door and enclosure.
One attempt to solve the sealing problem is described, for example, in the document DE-A-1 906 621. In this approach, the oven door comprises:
a rigid outer wall hinged along a first side to a first edge of the enclosure, PA0 a first plate, of a size slightly greater than the opening of the enclosure, formed so as to fit over the enclosure opening and close it in the closed position, the inner plate being movably fixed to the outer wall opposite its inner face, to which it is connected by connection means allowing the relative movement of the inner plate perpendicularly to the outer wall, between two relative limit positions defined by stop means. The connection means comprise resilient means urging the inner plate away from the outer wall so as to apply it in the closed position against the front face of the enclosure. A seal is provided between the outer plate and the front face of the enclosure so as to provide sealing in the closed position. PA0 a rigid outer wall hinged along a first side to a first edge of the enclosure, PA0 a seal providing sealing between the inner plate and the front face of the enclosure in the closed position, PA0 an inner plate, whose dimensions are slightly greater than the opening of the enclosure, adapted so as to fit over the enclosure opening and close it in the closed position, movably disposed in front of the inner face of the outer wall, to which it is connected by connecting means allowing the relative movement of the inner plate with respect to the outer wall for their relative movements towards or away from each other between two relative limit positions defined by stop means, the connecting means comprising resilient means urging the inner plate away from the outer wall and applying it, in the closed position, against the front face of the enclosure. PA0 the outer wall is provided with engagement means for selective locking thereof in the closed position, PA0 the inner plate is continuous, providing total sealing in the closed position, the connection between the inner plate and the connecting means introducing no possible passage between the inside and the outside of the enclosure, PA0 the outer wall has larger dimensions than the inner plate and comprises a peripheral portion which extends beyond the contour of the inner plate and which forms a protective flange whose edge is opposite the front face of the enclosure, PA0 passages are provided between the outer wall edges and the front face of the enclosure so as to permit natural air convection between the outer wall and the inner plate and to allow the steam to leave and be cooled and prevent its progression towards the front when the gas pressure prevailing inside the enclosure is sufficient to move the inner plate towards the outer wall against resilient means.
Such a structure is adapted for improving sealing at the level of the peripheral seal between the inner plate and the oven enclosure, but does not solve the problem of total sealing of the door. In fact, the inner plate is fixed to the outer wall by rods, a first end of which is fixed rigidly to the outer wall and the second end of which has a head forming an end of travel stop, the rod being mounted for sliding in an aperture of the inner plate. The steam contained in the enclosure may thus escape about the aperture around the rod.
Moreover, such a structure is not suitable for obtaining correct cooling of the outer wall of the door, for the inner plate comprises parts in contact with the outer wall and the air contained between the inner plate and the outer plate heats up rapidly by conduction through the plate and heats up the outer wall.